immunology Flashcards
where is periphery sites for immune system
other tissues and systems,
-skin, liver, gut, heart, brain, CNS, muscle, lungs etc
where did all lymphocytes arise
from stem cells in bone marrow
whar does self-renewing haematopoietic stem cell differentiate into
common myeloid progenitor and common lymphoid progenitor
what does myeloid progenitor differentiate in
innate immune system:neutrophi;, basophil, eosinophil and monocyte
what does common lymphoid progenitor differentiate in
adaptive immune system: lymphocytes
what are the hall marks of innate immune system:
1. speed early, rapid 2. duration short lived 3. repetitive -respond the same way each time 4. interactive - with other cells of the innate immune system - with cells of the adaptive immune system
what r the component of innate immunity:
- epithelial barriers
- cells in circulation and tissue
- phagocytes: neutrophils and macrophages
- exocytes:eosinophil, mast cells, basophils (release active mediators from granules) - molecules
- cytokines: tumour necrosis factor, interleukin 1 (IL-1)
- plasma proteins: complement proteins, mannose-bidning lectin, C-reactive protein.
what is thymus
site of T-cell maturation
- process of acquiring antigen-specific receptors\
- mature T-lymphoctes leaves the thymus and enter the circulation and the peripheral lymphoid organs
what r the 2 main types of lymphocytes
- B-lymphocytes
- T-lymphocytes
- helper t cell (Th)
- Cytotoxic T lymphoctes (CTL)
where did B lymphoctes derived
from common lymphoid progenitors in bone marrow
what does B lymphocytes form
part of the humoral immune response
what is the main function of B lymphoctes
to secrete antibodies
- antibodies are proteins that binds to EXTRACELLULAR ANTIGENS
what is the character of T help cell
- their surface expression of CD4 MOLECULE
how Th help other cells in immune response
- by release cytokines or
- via membrane bound molecules
what is the character of CTL
their surface expression of CD8 molecules
what is immature lymphocytes
- no not yet have antigen specific recpeotrs
- unable to respond to foreign antigens
- found in primary lymphoid tissues (bone marrow and thymus)
as the lymph passes through lymph nodes, antigen presenting cells in the nodes are able tosample microbial antigens hat may have entered through epithelia into tissues
T
dendritic cells can also pick up microbial antigens from the epithelial and other tissues and transport these antigens to lymph nodes
T
are B-cell and T cells zone mixed together
F.
B CELL AND T cells home to discrete zones in secondary lymphoid tissues
what is the function of secondary lymphoid tissues
- to drain lymph from the periphery
- to collect or trap antigens and antigen presenting cells (response is very localised)
- to provide a meeting place for
- recirculating T cells and
- DC arriving from the periphery - site of B cell - T cell interations
describe spleen
- blood entering the spleen flows through a network of channels (sinusoids) - blood borne antigens are trapped
- contain abundant phagocytes
- T lymphoctes are concentrated in periarteriolar lymphoid sheaths (PALS), surrounding small arterioles
what does specific mean
-adaptive immunity has exquisite antigen specificity
refers to the capapcity of the immune system to make a response to only 1 particular antigens
- property of B and T lymphocytes, which carry receptors unique for only 1 paricular antigen on their surface
what are antigens
antigens are substances that induce an immune response, such antigens are called immunogenic
what does the antigen specific receptors on lymphoctes binds to which part of antigens
a few amino cids or sugar only, they are called antigenic determinants or EPITOPES
what is naive lymphocytes
- mature lymphocytes that exist BEFOREantigen exposure
- have never engaged with cognate antigen
- the pre-cursor frequency of naive T cells specfic for antigen is very low
- migrate through and recirculate between secondary lymphoid organs
- typically die after 1-3 months if they dont make contact with antigen
- presentation of peptide + MHC molecules by DC activates naive T cells
what are activated lymphocytes
- mature lymphocytes taht have been presented with their foreign cognate antigen and been activated
- stop recirculating between lymphoid tissues
- migrate to periphral tissues and B-cell follicles to help B cells
what is effector lymphocyets
effector lymphocytes are acitivated lymphocytes that have differentiated into cells that produce molecules that function to eliminate antigens
whta does activated B lymphocytes differentiate into
antibody producing cells
antibodies from these called plasma cells, elimitae extracellular antigens
what does CD4+ Th cells do
they express surface molecules and produce cytokines, they help other cells (B-cells, macrophages, CTLs) to become fully activated and differentiate
